Gardaí in Carrick-on-Shannon, Co Leitrim are expected to continue the search today for a man who jumped into the river Shannon in the early hours of Sunday morning.
The man, named locally as Matthew Armstrong (20) of Cortubber, Co Roscommon, jumped from pleasure cruiser Moonriver at around 1am.
Mr Armstrong was out with friends and was on the deck of the boat when the incident happened. CCTV footage recovered from the boat by gardaí shows Mr Armstrong removing his shoes and socks before jumping over the railing of the boat.
The Irish Coastguard Sikorsky helicopter searched the river for a couple of hours from 8am yesterday using heat seeking equipment but could not find Mr Armstrong.
The Garda Underwater Unit and local divers from the Lough Ree Sub-Aqua Club and Roscommon Sub-Aqua Club continued the search until darkness, concentrating on the Rinnacurreen area, one mile from Carrick-on-Shannon.
Most passengers were drinking in the boat's covered lounge but a small number of smokers were on deck at the time and Mr Armstrong was in their company.
Passengers said the boat was travelling slowly when the incident happened and it stopped almost immediately afterwards. A life buoy was thrown into the water by a crew member.
Garda Sgt John O'Donnell said the victim did not appear to resurface once he dived in.
"There are very strong, difficult currents in the area of the river at Rinnacurreen and as soon as the life buoy was thrown in, it was carried away very quickly," he said.
"The river is wide and deep there and there are inlets and reeds and boggy areas. We were optimistic enough that we would find him using the helicopter but they searched and told us he was nowhere on the surface. He would have gone with the current."
The Moonriver is licensed to carry 110 passengers. It has a full bar licence and travels on the river every Saturday night. Entertainment on board includes traditional music and discos. While it can be hired for private parties, this was not the case on Saturday.